---
title: bin.hex_to_base64
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/cryptographic/bin-hex-to-base64
---

```
STRING bin.hex_to_base64(STRING s)
```

**Available in:** all subroutines

This function interprets a string resulting from the concatenation of the
parameters to the function as a hexadecimal string and it converts it to a
Base64-encoded sequence of the same bytes.

For example, `"009FC233"` on input will produce `"AJ/CMw=="` on output.

In particular this allows hexadecimal sequences with representations of the
octet `00` to be converted to the Base64 format without incurring the
truncation that would occur if this conversion was performed in two steps:
first by decoding the hexadecimal sequence to a VCL string and then by
encoding the VCL string to Base64.

See `digest.base64_decode()`
for details on the structure of Base64 encoding. In particular,
note that it is possible for two input strings to encode to the same
Base64 string.

## Errors

If the hex-encoded argument `s` is not valid hex, or if it is an incomplete
pair, then `fastly.error` will be set to `EINVAL`.

If this function does not have enough memory to succeed, then `fastly.error`
will be set to `ESESOOM`.

## Examples

```vcl
sub vcl_miss {
  set bereq.http.ShaBase64 = bin.hex_to_base64(digest.hash_sha256(bereq.http.Token ":salt"));
}
```

```vcl
sub vcl_error {
  synthetic.base64 bin.hex_to_base64("00" req.http.Message "1a");
}
```